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typeof Operator

Easy

In plain terms

typeof returns a string indicating the type: "string", "number", "boolean", "undefined", "object", "function", "symbol", "bigint". Note: typeof null is "object" (historical bug).

What you need to know

  • •Returns string type name
  • •typeof null is "object"
  • •Use for runtime type checks

Try it yourself

Copy the code below and run it in your browser console or a code editor:

typeof 42;           // "number"
typeof 'hello';     // "string"
typeof true;        // "boolean"
typeof undefined;   // "undefined"
typeof null;        // "object" (bug!)
typeof {};          // "object"
typeof [];          // "object"
typeof function(){};// "function"
typeof Symbol();    // "symbol"

Learn more

Dive deeper with these trusted resources:

MDNjavascript.infoTutorialsPointW3Schools